CODEWITHSUNDEEP
c++linked-list
mistletoe
mistletoe

Reputation: 493

insert at end of linked list

I am writing a simple function to insert at the end of a linked list on C++, but finally it only shows the first data. I can't figure what's wrong. This is the function:

node* Insert(node* head, int data)
{
    if (head == NULL) {
        head = new node();

        head->data = data;
        head->link = NULL;

        return head;
    }
    else {
        node* temp = head;
        while (temp != NULL) {
            temp = temp->link;
        }

        node* temp2 = new node();

        temp2->data = data;
        temp2->link = NULL;
        (temp->link) = temp2;

        return head;
    }
}

Upvotes: 2

Views: 11633

Answers (4)

Stargateur
Stargateur

Reputation: 26717

node* Insert(node* head, int data)
{
    if (head == NULL) {
        head = new node();
    }
    else {
        while (head->link != NULL) {
            head = head->link;
        }
        head = head->link = new node();
    }
    head->data = data;
    head->link = NULL;
    return head;
}

Upvotes: 0

Ritik Kumar Agrahari
Ritik Kumar Agrahari

Reputation: 56

change while(temp!=NULL) to while(temp->link!=NULL)

Upvotes: 0

melpomene
melpomene

Reputation: 85767

You can simplify your logic by doing this:

void Insert(node **pnode, int data)
{
    while (*pnode) {
        pnode = &(*pnode)->link;
    }
    *pnode = new node(data, NULL);
}

assuming you have a node constructor that initializes data and link from arguments.

Instead of calling it as

head = Insert(head, 42);

you'd now do

Insert(&head, 42);

Upvotes: 2

abhiarora
abhiarora

Reputation: 10430

Change the condition in while construct from:

while (temp!=NULL) {
    temp=temp->link;
}

To

while (temp->link!=NULL) {
    temp=temp->link;
}

In statement, temp->link = temp2, temp is a null pointer. You were dereferencing a NULL pointer.

To append a node at the back, temp pointer should point to the last node of the linked list. So, in the while loop, you need to just stop linked list traversal when you have reached the last node, i.e, the node whose link member points to nothing (has NULL). while (temp->link!=NULL) will stop at the last node as last node will have link member pointing to NULL.

Upvotes: 3

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